Bis-phosphines are widely employed as bidentate ligands in transition metal catalyzed reactions. It is known to prepare bis-phosphines via reduction of bis-phosphineoxide precursors obtained by reaction of 1,2-ethanediyl bis-tosylates or epoxides with a secondary phosphineoxide reagent [cf.: Synthesis (1983) 71-73].
There is great interest in 1,2-phenylene-bis-phosphines as bidentate ligands for transition metals. However, this synthesis is difficult aand thus hampers their wide application [cf.: Polyhedron 2 (1983) 303-304, Tetrahedron Letters 22 (1981) 1875-1878]. This is also true for the preparation of their usual precursors, i.e. 1,2-phenylene-bis-phosphineoxides [cf.: Organometallics 2 (1983) 1877-1879].